Appts. to measure valve lift in petrol-driven internal combustion (IC) engine

摘要

The appts has a permanent magnet (9) attached to a coupling (7) and generating a leakage field. A magnetic field sensitive sensor (13) is fixed near the coupling and measures the angle to the coupling. The measurement value from the sensor (13)is fed to a control unit (14), which calculates the position of the coupling from the angle measurement and so calculates the torsion of both camshafts (2,3) relative to each other and the valve lift. The magnetic field sensitive sensor (13) has a field- dependent resistance and a magnetorestrictive Giant-MR-layer system so the output value depends ONLY on the direction of magnetic field and not on the field strength. The temperature dependence of the sensor resistance is compensated by a bridge circuit.